What is the requirement for the armor of Type AC cable when used as an equipment grounding conductor?

The requirement that the armor of Type AC cable can be used as an equipment grounding conductor without the need for an insulated copper equipment grounding conductor is based on the design and construction of Type AC cable. This type of cable has a flexible armor that is inherently effective for grounding purposes due to its metallic characteristics.

When utilizing the armor as the grounding means, it is essential to ensure that the armor maintains continuity and is properly connected at both ends. This provides a reliable path to ground for fault currents, which is critical for safety and protection. The ability to use the armor directly eliminates the necessity for an additional insulated equipment grounding conductor in specific installations where the use of the armor meets the code requirements and is authorized.

In contrast, the other choices either imply that additional grounding measures are always required or suggest limitations that are not aligned with the accepted standards and practices for using Type AC cable. For instance, requiring an insulated grounding conductor would go against the flexibility and efficiency provided by the armor itself. Constraints related to fittings are also unfounded, as Type AC cables can indeed be effectively utilized with various compatible connections as long as the grounding provisions are upheld.